


Oil and Water

by javabi



Category: Supernatural
Genre: Alternate Universe - Future, Declarations Of Love, Demon Dean Winchester, End of the World, Hate to Love, King of Heaven Cas, King of Hell Dean, M/M, like wayyyy into the future
Language: English
Status: Completed
Published: 2014-07-14
Updated: 2014-07-14
Packaged: 2018-02-08 20:57:40
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,602
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1955901
Author URL: https://archiveofourown.org/users/javabi/pseuds/javabi
Summary: <blockquote class="userstuff">
              <p>Several hundred years after Dean Winchester became a demon and took over the legions of Hell, Castiel finds himself torn between hating the man Dean has become and loving the man he once was.</p>
            </blockquote>





	Oil and Water

There was no one in the universe who Castiel hated more than the King of Hell.

And it wasn’t just because he was Heaven’s leader. Of course that had _something_ to do with it (as a divine being he was obligated to hate that demonic aberration – such rivalry was coded into the core of his very being), but mainly it was personal.

Dean Winchester _had_ caused Castiel’s fall from Grace, after all. That was centuries ago, but such acts were not easily forgiven.

Once, eons before the third apocalypse, before the fall of humankind, before hordes of demons were unleashed upon the world in one of the young Knight’s many rages, Dean had been a good man.

The Righteous Man, they had called him. Destined to use the power of love and a little Hollywood flair to save the world, along with his wayward baby brother and a fallen angel who had fallen in more ways than one.

Castiel laughed bitterly. He would have _loved_ to have seen the look on Fate’s smug face when she’d realized how wrong _that_ particular prophesy had turned out.

Oh, they’d saved the world. Somehow. But what did that matter when four years later Dean gave up his humanity to take down one smarmy angel with a typewriter? What was worth saving a world that didn’t have a living, breathing, _human_ Dean Winchester in it?

Rage boiled in Castiel’s gut as he remembered all that he had given up to help that man. His family, his powers, even his own dignity. And for what, in the end? The rise of one demon and the fall of all humankind? It didn’t matter that Metatron had eventually seen how formidable an opponent Dean was, and given Castiel his Grace back. It didn’t matter that Castiel had then murdered his former tormenter for killing Dean. It didn’t even matter that Sam and Castiel had both survived Dean’s inhuman wrath, because these small victories were _nothing_ compared to the ensuing chaos of three thousand years.

The Earth was worthless now, a scarred, blazing rock hanging in space like a festering wound, all traces of life gone forever. It had been thousands of years, and still angels and demons fought over the stupid thing. Clawing at some semblance of ownership, no doubt. Desperate attempts to show who was really in charge. Castiel wasn’t sure why he kept his armies at it, other than the fact that the constant warring gave him and his soldiers something to do.

That’s what Castiel kept telling himself, anyway. It was easier than admitting that the fury churning in his stomach was anger at Dean, rather than at himself for still loving the former human despite everything.

-O-

There was no one in the universe who Dean hated more than the Ruler of Heaven.

“Get back to your fucking post!” he barked at a passing demon, who yelped and scurried up the battlements as quickly as possible.

Fighting a pointless war was more difficult than it seemed, Dean learned. Maybe “pointless” was the wrong word; he was always more than happy to see a few angels brutally murdered, choking on their own blood and writhing in piles of their own guts. These acts were invigorating, even if they didn’t involve the one angel he was _really_ hoping to kill off.

Oh, the centuries he’d spent envisioning that day.

He knew exactly how he’d do it: slowly, agonizingly, using every technique that old wash-up Alistair had shown him long ago. Castiel deserved to suffer, after what he’d done. The dumbass angel had kickstarted another apocalypse to try and stop Dean’s meteoric rise to power. He’d even dragged Sammy into it, the bastard. Luckily it took more than a measly old apocalypse to take out Dean Winchester, but the intent had annoyed him. So much for that fallen angel who had given everything to protect humanity all those years ago. Plus, y’know, _Sammy_.

His little brother had died long ago of old age, surrounded by grandkids and survived (for a few years) by his adoring wife, Adrienne. Sam was in Heaven, of course, and Dean tried not to be too bitter about it. Existence was better up there, even if it meant that Castiel could see Sam any time he wanted and Dean… well, Dean couldn’t. Remembering this fact, the King of Hell hurled a knife at the wall nearby with a shout of anger, a small group of demons scattering in its wake.

Dean Winchester wasn’t the kind of guy to have a bunch of useless regrets, but even he admitted that taking on the Mark of Cain might have been a mistake.

Still, there was nothing to be done about it now. And while Dean had these awesome powers he was certainly going to use them. It had been a while since the former hunter had physically seen Castiel, but rumor had it that the idiot still had a bit of a soft spot for Dean Winchester. The next time they came into contact, Dean would make sure to use that knowledge to make Castiel squirm in pain.

A wicked grin slithered across Dean’s face at the thought.

-O-

It was a few hundred years before the two of them saw each other again.

They forged an uneasy truce that day, but only out of necessity: Eve had broken out of Purgatory and was rounding up troops to bring back to Earth with her. Dean and Castiel both agreed that the last thing they needed was another faction to fight against, so they united their armies to take her out. The battle was quick, efficient, and decisive. Both sides remained professional, and after it was over they went their separate ways.

Not long after that things were back to normal, and they started brutally killing each other again.

-O-

That temporary truce planted a seed of forgiveness. It wasn’t long before the two armies would regularly unite (for only a few days, at the most) to eradicate a common threat. Both Dean and Castiel refused to acknowledge the strangeness of their situation: one week the armies were literally tearing each other to pieces, and the next they were fighting side by side. One minute they broke each other down, the next they held each other up. It was like the angel and the former hunter’s history was being replayed on a huge scale right before their eyes.

They forged many solid truces after that, simply because they wanted to.

-O-

Things didn’t _really_ come to a head until Crowley showed up.

Both the armies of Heaven and Hell had arrived immediately when the former king of the crossroads had appeared, bold as brass, in the middle of what had once been the Scottish countryside. Unluckily for him, he found himself perched on a blazing rock of earth between a battalion of angels and a battalion of demons.

Dean, who maintained his usual position at the front of his hellish legion, growled not at Crowley, but at Castiel. “What the hell are you doing here?”

“I want my revenge.”

“Oy!” Crowley interceded, his voice quivering somewhere between anger and fright. “What have I ever done to you? I’m the one who should be getting my revenge, Feathers, after the double-cross you pulled on me—“

“Shut up,” Dean spat. The demon fell silent instantly. “He’s right, Castiel – what do you want revenge for anyway?”

Castiel stood unflinchingly with his shoulders back and his chin held high. He replied calmly, “He stole your humanity, Dean.”

Both Crowley and Dean gaped at him as though the angel had just announced his desire to star in a ballet. “Yeah, that’s why I’m here. Doesn’t explain why that matters to you though, Castiel.” Dean said slowly, hardly daring to believe what he was hearing.

“You think I don’t care that this – this _creature_ is the one responsible for taking my Righteous Man away from me?” Castiel hissed, apparently not worried about maintaining his aloof dignity. “He took your life, your autonomy, and your personhood. He must be punished.”

“Well, now, boys I wouldn’t say I—“

“SHUT UP!” This time Dean and Castiel shouted it together. Crowley snapped his mouth shut.

So it was true after all: Castiel, the Ruler of Heaven, still loved Dean. Smiling gleefully at this realization, Dean thought about how to use this information to his advantage: how could he twist the angel’s love into something ugly, something barbaric and full of agony? Surely it wouldn’t be too hard.

Then Dean happened to glance at Castiel’s face.

The angel looked peaceful, but determined. Dean knew that look: it was an expression that said Castiel was ready to die for whatever he had set his mind to, to fight for it no matter what the cost. It was dangerous and terrifying and caused by Castiel’s feelings for _him_. For Dean.

It had been a long time since anyone had cared that much about Dean Winchester. In that moment, Dean decided that Crowley would be eradicated by both himself and Castiel, together. The nerdy little dude with wings deserved it for loving such an unlovable creature so fiercely for all these years.

“Cas…”Dean said quietly, so that only they could hear. It had been a millennia since the nickname had rolled off his tongue.“don’t ever change.”

Castiel’s smile shone brighter than the entire Heavenly Host at his back. The recognition that their relationship was just as strong as it had been an eternity ago was better than a thousand “I love you”s.

Those came next, of course.

-fin-

 


End file.
